Secondary battery



(No Model.)

L. DUNCAN.

SECONDARY BATTERY.

Patented Dec. 11, 1888.

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UNITED STATES PATENT OFFICE.

LOUIS DUNCAN, OF BALTIMORE, MARYLAND.

SECON DARY BATTERY.

SPECIFICATION forming part of Letters Patent No. 394,474, dated December 11, 1888.

Application filed May 12, 1888. Serial No. 273,695. (No model.)

To all whom it may concern:

Be it known that I, LOUIS DUNCAN, of Baltimore, in the State of Maryland, have invented a certain new and useful Improvement in Secondary Batteries, of which the following is a specification.

My invention relates, mainly, to secondarybattery plates or electrodes, such as are set forth and claimed in my application, Serial No. 273,692that is, those in which the core or supporting-plate is provided with a protectingcoating impervious to acid solutions, whereby local action bet-ween such core and the active material is avoided. As is set forth in the application just referred to, this use of a protective coating enables me to use for the core or supporting-plate metals other than lead or lead-alloy and having advantages over lead or its alloys in strength or conductivitysuoh as iron or copper, for instance. I have found, however, that, although I may use such metals for the main portion of the core, it is often advantageous that at least the surface of the core should be of lead; because the coating applied in the manner set forth in the application referred to adheres well to a lead surface, and because, if local action should by any possibility occur, it will be less injurious with a lead surface than with one of a different metal.

My invention, then, consists, mainly, in a compound core or supporting-plate for a sec: ondary-battery elementthat is, one composed mainly of a metal other than lead and having a surface of lead, the same being provided with an impervious protectingcoating, as above explained, and also in the combination of such a core with other portions of the battery, as hereinafter set forth and claimed.

I take a thin plate of iron, copper, bronze, or such other metal as may be selected, and which may have a plane surface or be provided with cells or depressions, and I wash the same with lead, so as to form a thin surface-coating of that metal. The core or supporting-plate thus formed I prefer to then cover with a hard dense even impervious coating of an oxide of lead by making the same the anode in an electrolytic bath composed of an alkaline solution of a salt of lead, employing a weak current, continuing the operation for a long time, and agitating the solution during the process.

This process I do not claim herein, it being claimed in my application, Serial No. 273,693 of even date herewith. Neither do I claim herein the core or supporting-plate provided with such a protective coating, since this is claimed in my application, Serial No. 73,692, above referred to.

I apply the active mater.ial )referably loose or porous peroxide of'lead-either by the mechanical process or by a suitable electrolytic process. I prefer to employ the process set forth and claimed in my application, Serial No. 273,694 of even date herewith.

My invention is illustrated in the accompanying drawings.

Figure l is a plan view of a complete plate embodying my invention,with portions of the successive layers of material broken away to show those beneath them; and Fig. L, a crosssection of a portion of the same.

A is the base, which is a thin plate of iron, copper, or other suitable metal or conducting material.

a u is the thin lead coating thereon.

Z) Z) is the impervious coating of a hard dense oxide of lead.

0 c is the active material, being loose or porous peroxide of lead.

It is evident that my invention is also readily applicable to grids or supporting-plates provided with cells for holding the active material.

\Vhat I claim is l. The compound core or supporting-plate for secondary batteries, provided with an impervious protecting-covering, substantially as set forth.

2. The compound core or supporting-plate for secondary batteries, in combination with an impervious protecting-covering and extern al active material, substantially as set forth.

3. A core or supporting-plate for a secondary-battery element, having, in combination, a plate of conducting material other than lead and having a lead surface and an impervious protectin g-covering, substantially as set forth.

i. In a secondary-battery element, the combination of a plate of conducting material other than lead and having alead surface, an impervious protecting-covering, and external active material, substantially as set forth.

5. A core or supporting-plate for a secondary-battery element, having, in combination, a plate of conducting material other than lead and having a lead surface and a hard dense impervious protecting-covering of an oxide of lead, substantially as set forth.

6. In a secondary-battery element, the combination of a plate of conducting material other than lead and having a lead surface, a

hard dense impervious protecting-covering of an oxide of lead, and external active material, substantially as set forth.

7. In a secondary-battery element, the combination of a plate of conducting material other than lead and having a lead surface, a

hard dense impervious protecting-covering of LOUIS DUNCAN.

Witnesses:

' W. Soo'rr GOSNELL,

P. H. C. STITOHER, Jr. 

